Floating solar still



Jan. 21, 1958 s. LIGHTER 2,820,744

FLOATING SOLAR STILL Filed Nov. 5, 1956 ATroR/VEJ/s.

United States Patent Q FLOATING SOLAR STILL Stephen Lighter, Madison, Wis.

Application November 5, 1956, Serial No. 620,293

6 Claims. (Cl. 202-234) The present invention relates in general to the art of converting polluted liquid into pure water, and it relates more specifically to improvements in the construction and operation of solar heat actuated stills for transforming v converters have embodied complicated 'systems andmechanism for producing and removing the purified liquid, while others did not function automatically and tinuity of operation, and none of the previous solar still assemblages have proven entirely satisfactory primarily because of their bulk, cost, lack of reliability, and inefciency.

It is therefore an important object of the present invention to provide a compact and automatically functioning solar still adapted to rapidly and effectively distill sea water or the like.

Another important object of this invention is to provide a buoyant seat water distilling unit adapted to most effectively utilize solar heat to continuously convert such water into palatable liquid while oating on the sea.

A further important object of the invention is to provide an improved sea water distilling device of relatively small size but of considerable output capacity especially adapted to ride upon the open sea and to produce and deliver pure drinking liquid without the aid of complicated condensing coils and other mechanism.

Still another important object of my invention is to provide an inexpensive but reliable solar still of maximum eiciency capable of being carried on life rafts and of oating upon sea water or the like while converting such water into potable liquid devoid of all impurities.

These and other more specific objects and advantages of the invention will be apparent from the following description.

A clear conception of the features constituting the present improvements, and of the construction and functioning of a solar still unit embodying the invention, may be had by referring to the drawing accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the several views.

Fig. 1 is a part sectional top view of a typical solar still constructed in accordance with the invention, the section having been taken along the line 1-1 of Fig. 2; and

Fig. 2 is a central vertical section through the same still unit, taken along the line 2-2 of Fig. 1, and showing the device in action.

required considerable attention in order to insure con- While the invention has been illustrated and described herein as having been embodied in a buoyant solar actuated unit especially adapted for the distillation of sea water and equipped with means for preventing sea urchins and other impurities from entering the final product, it is not intended to restrict the improved features to such an assemblage; and it is also contemplated that specific descriptive terms employed herein be rgiven the broadest possible interpretation consistent with the actual disclosure.

Referring to the drawing, the improved buoyant solar still illustrated comprises in general, an imperforate dome shaped outer casing having an annular upright side wall 4 spanned at its upper end by a top deck or enclosure 5; an inner upright annular wall 6 located within and spaced from the casing side wall 4 but coacting therewith to provide a deep upwardly open annular trough 7, the inner wall 6 having an unobstructed bottom opening 8 communicable with the ambient atmosphere and an upper unobstructed open end 9 spaced from the casing top enclosure 5; a liquid pervious barrier 10 spanning the interior of the inner wall 6; and an outlet nipple 11 for the trough 7 communicable with a receptacle for the distilled liquid through a flexible conduit 12.

The main casing and the inner wall 6 are preferably formed of relatively heavy and durable material such as transparent plastic or glass, and the side wall 4 of the casing may be provided with a lower inwardly directed integral flange 14 to which the lower end of the inner wall 6 may be detachably attached by means of screws 15 or the like in order to provide for cleaning access to the bottom of the trough 7. While the walls 4, 6 and trough 7 are shown as being truly circular, they may be of any other continuous shape, and the top deck or enclosure 5 of t-he casing may be formed integral with or separable from the side wall 4, and is preferably curved as shown in order to conduct and drain any condensate deposited thereon into the trough 7.

The liquid pervious barrier 10 shown comprises a ne screen capable of preventing animal life and other small particles in the sea water 17 in which the unit is normally floated, from entering the condensing space 18 beneath the casing top enclosure 5. This screen barrier 10 may be removably confined along its periphery, within an annular groove 19 in the inner wall 6, and the upper outer surface of the dome top enclosure 5 is preferably covered with a dark heat absorbing coating, while the inner surface of this enclosure S and the barrier screen 10 are preferably coated with heat reilective layers of aluminum or the like. The conduit 12 may be a flexible hose or the like sealingly attached to the nipple so as to prevent free access of ambient air to the space 18, and this conduit 12 together with similar outlet conduits of several other like solar units, should have its outlet end immersed in liquid Vwithin the pure water receptacle so as to produce a siphoning effect.

When the improved solar still has been properly constructed and assembled as above described, one or more of the units depending upon the demand for pure distilled liquid required, may have their delivery conduits applied to a suitable receptacle, whereupon the individual units may be floated upon the open sea. As depicted in Fig. 2, each of the solar stills when oated, should be of suicient heft and depth to cause the lower portions of the walls 4, 6 and of the trough 7 to be immersed to a considerable extent beneath the surface of the sea water 17. Upon being thus floated, sea water 17 Will fill the space beneath the barrier 10 through the bottom opening of the inner wall 6, and filtered sea water devoid of'psolids and animal life will rise into the space withinthe inner wall 6 above the pervious barrier 1u to a levei somewhat Patented Jan. 21, 1958 VWhen a oating unit is subsequently subjected to the` sun7s rays, the dark coated outer surfaceV of the top enclosure 5 will absorb considerable' heat and thereflectively coated-'lower surface-'of the VdecloS together with thev likewise coated'barrier"willreect heat into the-space 18l thereby evaporating liquid fromw.ithin the inner wall 6 above` the barrier 10; Thevapor'thuseformedewill condense upon contacting the inner dome surfaces'Sandl the outer-surface of Athezinner wallfz-whieh areaimmersed within the? cool, sea; water-1 la7, andV the- Aconde-risatewill accumulatewithin ther-trough 'l-frompwhich it may. be. constantly siphoned or. otherwisewithdrawn throughthe.

nipple.f llzand .conduit 12;: Thef'deliveryof thispfneslr liquid froml each. unitV is alsoematerially faided'bvnthe hydrostatic pressure existingtwithin .the condensing space;-

18, and any impurities removedbydis-tillationbwill gravitate backziinto.. the .sea through theA perforatedV barrier 10.--

FromgV the foregoing;detailedgdeseription ojfqtheconstr-uction and fun;tioningsoftthe devieatit shouldbeapparent; that the present inventionin fact1,.p1DYClan-efcientq solar :still for sea `Water,which is extremely pl compact in structure and automat ic oper the condensing lchamber or spacelfis hermeticaliyseaied the airr pressure within this chamber remains-substanft ly 1 constant, andV no foreign matter can. enterths .Sealed 93@ andinto .the trough 7. due to thepnovision of. theperviousor perforated barrier 10.r Theunit whenjoated provides 'Y ample surface exposed vtto-cool condensingliquidanl the, transparentwall's, and coated surfaces Yof thev dome f topS and of the'barrier-,l0g insuremosteective applica? v tion ,of `the available heat. Th? improved assemblageifs devoid o'f all mechanisrn,l andthevaous pensare` .Conf

venientlyse'parable for cleaninguandf inspection purposes-v and `may b'e constructed at morderatercost. The unit is especially adapted for use on life raftsorthelile, but

may be manufactured in various sizes vfprdiverse'uses,

and the still has proven highly satisfactory and successful for the distillation of brine into'potable .drinking water.

It should be understood that itis not desired -to limit this inventionto thel exact details of construction and operation of` the solar heated still jherein specikcally shown'and-described, for variousvmodiications within the scope-of-the appended claimsimay occurfto( persons-skilled in the art.

v.IVv claim:

1. Infaesolarstill, an imperforate-dorne-shapedf'buoyant' outer-casing having a continuous ysidewall spanned -atits upper A'end by a Atopf'enclosure a continuous.-innei-AvvallVVA withinsaidf--casing side Wall andcoactingftherevvithto V provide an-upwardly openltroughfbetween saidfwa1ls, `said. innerrwall'havingan openilower end communicating' withv the ambient atmospherean-d an opemupperfend spaced from said ,topenclosureand communicating with said trough, andY meansffor conductingtliguid 'from '.withinsaid trough. f

2. In a solar still, an imperforate dome shaped buoyant outer casing having a continuousV side Wall spannedv atits-a upper end by a top enclosure, a continuous inner wall within said casing side wall' and coacting therewith to provide an upwardly open trough between said walls, said inner wall having an open lower end communicating with the ambient atmosphere and an open upper end spaced from said top enclosulreand communicating with said trough, a liguidpervious barrier spanning the interior of said inner wall, andconduit means for conducting liquid from within said ticguglrf 3 .In .a Solar still, an. ,ininerrate 4.derrleshaprd buoyant outer casing havingrv a continuous annular sidefvvall spanned at its upperrendfbv an .upvvardly convex top enclosure, a continuousinner annular wall within said casing side wall and coacting therewith to provide an upwardly opentrough between said walls, said inner wall having an unobstructed open `lowernend communicating with f the ambient atmosphere andyan; unobstructed open uppenend spaced -fromsaid-topI enclosure toforma condensing chamber communicating `witlislaid though;-v

and means lfor conducting liquid from-.Within said trough.. 4. In a solar still,animperioratedomeshaped buoyant. outer casing havingN a.V continuous annular Y side wall spanned .at i-ts:..upperV '.en'd by.y van vupwardly y convex top; y enclosure,'a continuous inner annular: wall wit-hinsaid.;

casingYg-side.' lwall and .coacting-.f.therewithY.to provide an said vtop tenclosur. Chamber; :communie Haagh;

Sala asglarfstillf aatimnelgrafedo cpm. :s

said inner wallhaving 'ano enflo`.v'{'erV endnormally in Said trQushf`No references cited.

viouseb arrier @Spanninszthe interi@ of said imageriwal-1,,and;Y

r emanating-:liquid from within phere and an' open`uppe'r end'spaced'rdnfsaid enclosure 4t-o' `Qrm, .a; heirmetically sealed condensing trough and means tor 

4. IN A SOLAR STILL, AN IMPERFORATE DOME SHAPED BUOYANT OUTER CASING HAVING A CONTINUOUS ANNULAR SIDE WALL SPANNED AT ITS UPPER END BY AN UPWARDLY CONVEX TOP ENCLOSURE, A CONTINUOUS INNER ANNULAR WALL WITHIN SAID CASING SIDE WALL AND COATING THEREWITH TO PROVIDE AN UPWARDLY OPEN TROUGH BETWEEN SAID WALLS, SAID INNER WALL HAVING AN OPEN LOWER END COMMUNICATING WITH THE AMBIENT ATMOSPHERE AND AN OPEN UPPER END SPACED FROM SAID TOP ENCLOSURE TO FORM A LIQUID SEALED CONDENSING CHAMBER COMMUNICATING WITH SAID TROUGH, A LIQUID PERVIOUS BARRIER SPANNING THE INTERIOR OF SAID INNER WALL, AND 